1. Field of the Invention
The invention relates to a door operator, in particular a swing door operator.
2. Description of the Related Art
Such a door operator is known from DE 295 21 068 U1. An overhead door closer with a slide rail linkage is known from DE 40 38 720 C2, which has a cam drive unit allowing for an optimum door moment curve and a comfortable operation. In principle this overhead door closer would thus be suitable as a door operator as well; however, experiments conducted during the course of the invention have shown that applying oil pressure to the drive unit results in a very unfavourable transformation of the hydraulic pressure into the resulting movements of stroke/rotation and repeated stroke. Since about 75% of the output capacity to be applied is required for loading the spring force accumulator of such a door closer, whereas only about 25% of the output capacity needs to be delivered by the system for accelerating the door. As it is furthermore desirable to keep the narrow structure of such a door closer for door operators as well, the dimensions of the structural components cannot be adapted to the extreme high loads. Thus, although functionally and technically advantageous, the known overhead door closer is not suitable as a door operator.
Another swing door operator is known from DE 197 56 496 C2. This swing door operator has an electromechanical drive unit, which is provided with a drive motor and a gear and with a subsequent power transmission unit for the connected door. The power transmission unit has a spindle with a spindle nut partially overlapping the former, which spindle is non-positively and positively connected to a toothed rack. Although this swing door operator can be installed concealed, the door moment curve is not as optimal as with the above described door closers having the cam technology. However, on account of the larger construction width, installation in standard profiles is not possible.